Front cover of the first edition of Lenin's Materialism and Empirio-Criticism, published in Moscow in 1909 under the pseudonym "Vl. Ilyin."

Materialism and Empiriocriticism (Russian: Материализм и эмпириокритицизм, Materializm i empiriokrititsizm) is a philosophical work by Vladimir Lenin, published in 1909. It was an obligatory subject of study in all institutions of higher education in the Soviet Union, as a seminal work of dialectical materialism, a part of the curriculum called "Marxist-Leninist Philosophy". Lenin argued that human perceptions correctly and accurately reflect the objective external world.

The book, whose full title is Materialism and Empirio-criticism. Critical Comments on a Reactionary Philosophy, was written by Lenin from February through October 1908 while he was exiled in Geneva and London and was published in Moscow in May 1909 by Zveno Publishers. The original manuscript and preparatory materials have been lost.

Most of the book was written when Lenin was in Geneva, apart from the one month spent in London, where he visited the library of the British Museum to access modern philosophical and natural science material. The index lists in excess of 200 sources for the book.

In December 1908, Lenin moved from Geneva to Paris, where he worked until April 1909 on correcting the proofs. Some passages were edited to avoid tsarist censorship. It was published in Imperial Russia with great difficulty. Lenin insisted on the rapid distribution of the book and stressed that "not only literary but also serious political obligations" were involved in its publication.

The book was written as a reaction and criticism to the three-volume work Empiriomonism (1904–1906) by Alexander Bogdanov, his political opponent within the Party. In June 1909, Bogdanov was defeated at a Bolshevik mini-conference in Paris and expelled from the Central Committee, but he still retained a relevant role in the Party's left wing. He participated in the Russian Revolution and after 1917, he was appointed director of the Socialist Academy of Social Sciences.

Materialism and Empiriocriticism was published in over 20 languages and acquired canonical status in Marxist–Leninist philosophy.